1. Field of the Invention
The present invention relates to the field of bicycle forks and in particular, to the spring system incorporated into bicycle forks.
2. Description of the Prior Art
A bicycle fork is the portion of a bicycle that holds the front wheel and allows the rider to steer and balance the bicycle. A fork consists of two fork ends which hold the front wheel axle, two blades which join at the fork crown, and a steering tube which is attached to the handle bars.
On most mountain bicycles, the fork contains a set of shock absorbers so that the blades typically consist of upper and lower telescoping tubes which are called legs.
A portion of the legs is the shock absorber which usually consists of two parts: a spring and a damper. The spring can be a metal coil but more commonly is now compressed air. Air springs utilize the thermodynamic property of gasses that their pressures increase as they are compressed adiabatically. The spring constant can be adjusted by adjusting the air pressure. This allows a fork to be tuned to a rider's weight.
The damper usually forces oil to pass through one or more small openings in the suspension fork.
In a traditional system, the compression rod which is usually a hard material such as aluminum or plastic pushes directly on the piston. The piston also usually is made out of aluminum, plastic or similar material. Until the load in the compression rod exceeds the static friction of the piston assembly seal, the suspension does not compress. The result is an undesirable harshness.
U.S. Pat. No. 6,592,136 discloses a standard connection between a piston assembly and a compression rod assembly. U.S. Pat. No. 2,212,759 discloses rubber isolators 28 and 47.
There is a significant need for an improved suspension system in a bicycle fork that addresses the problems set forth above.